Fusion-pore expansion during syncytium formation is restricted by an actin network.
Cell-cell fusion in animal development and in pathophysiology involves expansion of nascent fusion pores formed by protein fusogens to yield an open lumen of cell-size diameter. Here we explored the enlargement of micron-scale pores in syncytium formation, which was initiated by a well-characterized fusogen baculovirus gp64. Radial expansion of a single or, more often, of multiple fusion pores proceeds without loss of membrane material in the tight contact zone. Pore growth requires cell metabolism and is accompanied by a local disassembly of the actin cortex under the pores. Effects of actin-modifying agents indicate that the actin cortex slows down pore expansion. We propose that the growth of the strongly bent fusion-pore rim is restricted by a dynamic resistance of the actin network and driven by membrane-bending proteins that are involved in the generation of highly curved intracellular membrane compartments.
Chen
Andrew
A
Section of Membrane Biology, Laboratory of Cellular and Molecular Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892-1855, USA.
Leikina
Eugenia
E
Melikov
Kamran
K
Podbilewicz
Benjamin
B
Kozlov
Michael M
MM
Chernomordik
Leonid V
LV
D000199:Actins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D016367:Baculoviridae / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D022082:Cellular Structures / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D047630:Depsipeptides / Q000494:pharmacology; D015726:Giant Cells / Q000378:metabolism*; D007313:Insecta; D008561:Membrane Fusion / Q000502:physiology; D018613:Microscopy, Confocal / Q000379:methods; D008954:Models, Biological; D053778:Thiazolidines / Q000494:pharmacology
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D047630:Depsipeptides; D053778:Thiazolidines; C057531:jasplakinolide; C037067:latrunculin A